Shortwave infrared imaging system

ABSTRACT

An example imaging apparatus that can operate at shortwave infrared (SWIR) wavelengths are provided. An example imaging apparatus may include a flexible elongate member having a distal end and proximal end. The flexible elongate member may include a shortwave infrared (SWIR) imaging sensor disposed at the distal end and a lens optically coupled to the SWIR imaging sensor and disposed at the distal end of the flexible elongate member, the lens configured to focus light energy at the SWIR wavelength onto the SWIR imaging sensor. The member may also include an illumination source configured to provide light energy at the SWIR wavelength at the distal end of the flexible elongate member for output to illuminate an object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior application Ser. No.16/254,686, filed Jan. 23, 2019, which claims the benefit of U.S.Provisional Application No. 62/647,007 filed on Mar. 23, 2018, theentire contents of both are hereby incorporated herein by reference.

STATEMENT OF GOVERNMENTAL INTEREST

This invention was made with U.S. Government support. The government hascertain rights in the invention.

TECHNICAL FIELD

Example embodiments generally relate to imaging systems and, inparticular, relate to imaging systems that include fiber optic bundlesto support imaging applications.

BACKGROUND

Imaging systems have proven to be extremely useful in many applications.In some instances, there is a need for an imaging system to captureimages in environments that are difficult to access due to the size ofimaging detectors. Examples of such environments may include, forexample, inside the human body, beyond a turn in a pipe or conduit, orinside a container or machine, such as a motor, that is currentlyoperating. With respect to medical applications, for example, detectorsizes may require large incisions for the detector itself to access theobject of interest for imaging purposes.

BRIEF SUMMARY OF SOME EXAMPLES

According to some example embodiments, an imaging apparatus that isconfigured to operate at SWIR wavelengths is provided. The exampleimaging apparatus may include a flexible elongate member. The flexibleelongate member may have a distal end and proximal end. The flexibleelongate member may include, for example, a shortwave infrared (SWIR)imaging sensor, a distal lens optically coupled to the SWIR imagingsensor and disposed at the distal end of the flexible elongate member,the distal lens configured to focus light energy at the SWIR wavelengthonto the SWIR imaging sensor, an illumination source configured toprovide light energy at the SWIR wavelength at the distal end of theflexible elongate member for output to illuminate an object, and one ormore control cables disposed within the flexible elongate member, thecontrol cables enabling movement of the flexible elongate member. Theimaging apparatus may also include a handle coupled to the flexibleelongate member and mechanical controls operably coupled to the controlcables for directing the flexible elongate member.

According to some example embodiments, another imaging apparatus isprovided that may comprise a distal end, a proximal end, a shortwaveinfrared (SWIR) imaging sensor disposed at the distal end, a lensdisposed on the distal end, the lens configured to focus light energy atthe SWIR wavelength on the SWIR imaging sensor, SWIR anti-reflectivecoating disposed on the lens, and an illumination assembly configured tooutput illumination at the SWIR wavelength adjacent to the distal endtoward an object, wherein the SWIR imaging sensor is configured toreceive imaging light energy at the SWIR wavelength reflected from theobject and focused through the lens.

An example method for imaging at the SWIR wavelengths is provided. Theexample method may comprise, for example, generating light energy at ashortwave infrared (SWIR) wavelength by an illumination source,projecting the light energy at a distal end of a flexible elongatemember to illuminate an object with the light energy at the SWIRwavelength, receiving imaging light energy at the SWIR wavelength fromthe illuminated object at a distal lens of the flexible elongate member,focusing the imaging light energy at the SWIR wavelength onto a SWIRsensitive compact imager via the distal lens, and transmitting imagedata from the SWIR imaging sensor to a display.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described some embodiments in general terms, reference willnow be made to the accompanying drawings, which are not necessarilydrawn to scale, and wherein:

FIG. 1 illustrates a block diagram of an example imaging apparatusaccording to some example embodiments;

FIG. 2 illustrates a distal end tip of a flexible elongate member of anexample imaging apparatus according to various example embodiments;

FIG. 3A illustrates a cross-section front view of a fiber of the fiberoptic bundle according to various example embodiments;

FIG. 3B illustrates a cross-section side view of an fiber optic bundleaccording to various example embodiments;

FIG. 4A illustrates a cross-section view a proximal end of the fiberoptic bundle of FIG. 3B taken at A-A according to various exampleembodiments;

FIG. 4B illustrates a cross-section view of an intermediate portion ofthe fiber optic bundle of FIG. 3B taken at B-B according to variousexample embodiments;

FIG. 5 illustrates an example endoscope according to some exampleembodiments;

FIG. 6 illustrates a block diagram of an example method for imagingaccording to various example embodiments;

FIG. 7 illustrates a block diagram of another example imaging apparatusaccording to some example embodiments;

FIG. 8 illustrates a block diagram of another example method for imagingaccording to various example embodiments;

FIG. 9 illustrates an example device to provide a focusing capability;and

FIG. 10 illustrates an example distal tip of an endoscope.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout.

As noted above, many current fiber optic bundles, which include coherentimaging fiber optic bundles, are specifically designed to operate in thevisible spectrum. However, many imaging applications would benefit fromimaging at other wavelengths that are not in the visible spectrum, suchas short wave infrared (SWIR) wavelengths. For example, many materialsbeing imaged, in particular biological tissues and fluids, may notsupport effective imaging in the visible spectrum due to issues withabsorption and scatter in many environments. However, absorption andscattering may be greatly reduced in such applications if the imaging isperformed at SWIR wavelengths. Unfortunately, many current fiber opticimaging bundles themselves may not be able to transmit nor supportimaging at SWIR wavelengths due to issues such as crosstalk between theindividual fiber cores of the bundle. Such crosstalk poses a technicalproblem that can inhibit the ability of the system to operate, forexample, at the SWIR wavelengths, and therefore the benefits of imagingat SWIR wavelengths cannot be realized.

Accordingly, an example imaging apparatus is described herein that iscapable of performing imaging at wavelengths in the shortwave infrared(SWIR) spectrum. The SWIR spectrum includes wavelengths from about 1.0micrometer to about 1.7 micrometers. Various example embodiments of theinvention may perform imaging at wavelengths, for example, of 1.5micrometers, between greater than 1.0 micrometer to 1.7 micrometers,outside of the near infrared spectrum and visible light spectrum, orincluding the SWIR spectrum, the near infrared spectrum, and the visiblelight spectrum. The imaging apparatus may take a number of forms and maybe implemented in a number of different applications. In some exampleembodiments, the apparatus may comprise an endoscope or a fiberscope.With respect to applications, the example imaging apparatus 100, asshown in FIG. 1, may be employing in medical imaging, mining, machinemaintenance and repair, or the like. Because example embodiments operatein the SWIR spectrum (i.e., at SWIR wavelengths as defined herein), suchapparatuses can realize significant advantages over, conventionalsystems, such as endoscopes and fiberscopes that operate in the visiblespectrum (i.e., between 0.4 to 0.7 micrometers) or in the near infrared(NIR) spectrum (i.e., between 0.700 to 1.00 micrometers).

In this regard, the ability to image at the SWIR wavelengths offers asignificant advantage with respect to reducing the scattering of lightenergy in the presence of lower density substances such as soft tissue.Imaging through, for example, biologic soft tissue can therefore beperformed with high quality and with deeper imaging penetration due tothe ability to operate at the SWIR wavelengths. As such, imaging at theSWIR wavelengths can offer increased imaging penetration into, forexample, the body for medical imaging and diagnostic, which can offer areducing in the physical impacts on the body. Additionally, thereduction in light scatter at the SWIR wavelengths can also reduceblurring and other effects of scattering thereby leading to improvedimage quality and higher diagnosis accuracy. These are just someexamples of the benefits of SWIR wavelength operation in the context ofmedical imaging, while other benefits may also be realized innon-medical applications.

An example imaging apparatus, according to some example embodiments, mayinclude a control assembly comprising an imaging detector configured toperform image capture at SWIR wavelengths. Additionally, the exampleapparatus may comprise a flexible elongate member that includes a fiberoptic bundle that operably couples to the imaging detector to facilitateimage capturing through the fiber optic bundle. According to someexample embodiments, the fiber optic bundle may be configured foroperation at the SWIR wavelengths to guide light energy reflected froman object of interest at SWIR wavelengths through the fiber optic bundleto the imaging detector for image capture. Functionally, the fiber opticbundle, due to its flexibility, length, and narrow cross-sectionaldiameter, may allow the imaging detector to capture images in locationswhere access may be limited (e.g., internal to a body or within a closedhousing of a machine).

However, many conventional systems that employ fiber optic bundles havea drawback in the form of inter-core crosstalk. In this regard, becausea fiber optic bundle includes a plurality of fibers. Each fiber mayinclude a fiber core and cladding. The fibers, and thus the cores may bein close proximity to each other, and the evanescent fields that leakinto the cladding of the fiber from the fiber core when guiding orpropagating light energy can impact adjacent fiber cores leading to anissue called crosstalk that causes the transfer of light energy betweena guiding fiber core to adjacent fiber cores. Additionally, because, insome instances, fiber cores may be fixed in adjacent parallel proximityacross the entire length of the fiber optic bundle, an active fiber core(e.g., a fiber core that is guiding light of high intensity) mayintroduce significant crosstalk onto an adjacent fiber core because thecores remain in an adjacent physical relationship across an entirelength of the fiber optic bundle. Additionally, while the degree ofcrosstalk may be dependent upon a number of factors, the wavelength ofthe light energy being guided by the fiber core may also effect thedegree to which crosstalk occurs, and the guiding of SWIR wavelengthshas been often found to commonly suffer from significant degrees ofcrosstalk between fiber cores. As a result, a technical problem existsrelating to the ability to perform imaging at the SWIR wavelengths usingfiber optic bundles.

According to some example embodiments, to reduce the impact of crosstalkin the fiber optic bundle, the fibers in at least an intermediateportion (or length) of the fiber optic bundle may be disposed in anon-parallel arrangement. In this regard, according to some exampleembodiments, two fibers of the fiber optic bundle need not be fixed inan adjacent, parallel alignment across the length of the fiber opticbundle. Rather, the fibers may be disposed in a non-aligned arrangementthat promotes a non-parallel positional relationship between the fibers.As such, because the fibers are not adjacent across the length of thebundle, crosstalk between the corresponding cores of the fibers may bereduced. According to some example embodiments, the reduction incrosstalk realized in this manner can facilitate operation at the SWIRwavelengths.

According to some example embodiments, to introduce a non-parallelpositional relationship between the fibers of the fiber optic bundle,the fiber optic bundle may be formed as a leached fiber bundle.According to some example embodiments, a leached fiber bundle may havean intermediate portion where the fibers are not aligned in parallel,but are permitted to move relative to each other. Such a structure maybe formed via a leaching processes where a fiber optic bundle preform,that includes leachable spacers between the fibers, is, for example,subjected to an acid etch bath. After the spacers are leached away viathe acid etch bath, the portions of the fibers that were subjected tothe bath may be free to move relative to each other and be flexed orbent. However, to maintain coherency, the ends of the fiber optic bundlemay remain fixed and the positioning of the fibers may be secured at theends. As such, according to some example embodiments, this leachedarrangement of the fibers can support a reduction in crosstalk andtherefore facilitate operation of the example imaging apparatus at theSWIR wavelengths due to the non-parallel arrangement of fibers.

Having described some example embodiments in general terms, FIG. 1provides a more detailed example embodiment of an imaging apparatus 100in the form of a relational block diagram. The imaging apparatus 100 maybe any type of imaging device including, but not limited to, anendoscope, fiberscope, or the like. In this regard, the imagingapparatus 100 or a portion thereof, may be a handheld device with, forexample, a handle to permit a user to position and operate the device.The imaging apparatus 100 may include a control assembly 134 and aflexible elongate member 110, where the control assembly 134 is operablycoupled to the flexible elongate member 110.

The control assembly 134 may include the imaging detector 140. Theimaging detector 140 may be any type of device that is capable ofcapturing light energy, including light energy in the SWIR spectrum, andconverting the received light energy into electrical signals fordelivery to processing circuitry (e.g., processing circuitry 145) forimage processing to develop a corresponding image. In this regard, theimaging detector 140 may be configured to receive imaging light energyat a SWIR wavelength that has been reflected from an object of interest165 and guided to the imaging detector 140 via the fiber optic bundle115. According to some example embodiments, the imaging detector 140 maybe configured to perform imaging at a wide range of wavelengths, whichmay operate to permit imaging in both the visible spectrum and the SWIR.According to some example embodiments, the imaging detector 140 mayinclude an image processor and may be configured to perform some or allimage processing local to the imaging detector 140. The imaging detector140 may comprise any type of digital camera, sensor array (e.g., chargecoupled devices, active pixel sensors, etc.), or the like withsensitivity in the SWIR region of the electromagnetic spectrum.According to some example embodiments, an imaging detector 140 thatcomprises a digital camera may be specifically configured to operate tocapture images at the SWIR wavelengths. The imaging detector 140 may bedisposed at or towards a proximal end of the imaging apparatus 100(i.e., opposite a distal end 111 of the flexible elongate member 110 asdefined below) and may be operably coupled to the flexible elongatemember 110, and more specifically the fiber optic bundle 115.

According to some example embodiments, the control assembly 134 may alsoinclude a proximal optics assembly 135 that is operably coupled to aproximal end of the fiber optic bundle 115. The proximal optics assembly135 may include one or more lenses 136 configured to condition (e.g.focus) light energy received from the fiber optic bundle 115 forprovision to the imaging detector 140. In this regard, according to someexample embodiments, the proximal optics assembly 135 may include lensesshaped to magnify light energy in the SWIR spectrum from the fiber opticbundle 115 for projection onto the imaging detector 140.

According to some example embodiments, the imaging apparatus 100 mayinclude or be operably coupled to processing circuitry 145. Processingcircuitry 145 may be configured to receive electronic signalscorresponding to an image capture of light energy and generate an image.The processing circuitry 145 may be configured to transmit the image toa display 146 (e.g., a liquid crystal display that may be stand-alone, acomponent of smartphone or tablet, or the like) for viewing by a userfor the purpose of analyzing the image, for example, to make adiagnosis, or to navigate the flexible elongate member 110 into adesired position to capture an image of an object of interest 165. Theprocessing circuitry 145 may include, for example, a processor and amemory, and the processor may be configured to execute instructions,code, or commands stored on the memory to cause the processing circuitry145 to perform the functionalities of the processing circuitry 145described herein. Alternatively, or additionally, the processor may be ahardware defined device configured to cause the processing circuitry 145to perform the functionalities of the processing circuitry 145 describeherein, and may be embodied as, for example, a field programmable gatearray (FPGA), an application specific integrated circuit (ASIC), or thelike.

As mentioned above, the control assembly 134 may be operably coupled tothe flexible elongate member 110. More particularly, the proximal opticsassembly 135 and the imaging detector 140 of the control assembly 134may be operably coupled to the fiber optic bundle 115 of the flexibleelongate member 110. The flexible elongate member 110 may be configuredto flex, bend, or otherwise articulate into various positions whilesupporting optical imaging functionalities. The orientation andpositioning of the flexible elongate member 110 may be controllable by auser to position a distal end 111 of the flexible elongate member 110 ina desired position to perform an image capture of an object of interest165. In this regard, the flexible elongate member 110 may have a distalend 111 which may, when in use, be closest to the object of interest 165for image capture, and the flexible elongate member 110 may have aproximal end 112, which may be opposite the distal end 111 and operablycoupled to the proximal optics assembly 135, or in some exampleembodiments physically coupled to a housing of the proximal opticsassembly 135.

According to some example embodiments, the flexible elongate member 110may include an illumination fiber 125, or a bundle of illuminationfibers. The illumination fiber 125 may be an optical fiber that, in someexample embodiments, is disposed within the flexible elongate member 110and extends from the proximal end 112 of the flexible elongate member110 to the distal end 111 of the flexible elongate member 110. Theillumination fiber 125 may be configured to deliver or guide lightenergy from an illumination source 150 to the distal end 111 of theflexible elongate member 110 for output into the environment about thedistal end 111 of the flexible elongate member 110 to illuminate anobject of interest 165. According to some example embodiments, theillumination fiber 125 may be configured to guide light energy in theSWIR spectrum from the illumination source 150 to the distal end 111 ofthe flexible elongate member 110. According to some example embodiments,the illumination fiber 125 may be a multi-mode fiber.

While the illumination fiber 125 may be disposed within the flexibleelongate member 110, the illumination fiber 125 may be a component of anillumination assembly. According to some example embodiments, theillumination assembly may include the illumination fiber 125 and anillumination source 150. According to some example embodiments, theillumination assembly may also include a diffuser 155, which accordingto some example embodiments, may be static or mechanically moveable orelectroactively moveable.

The illumination source 150 may be any type of light generating devicethat can generate light energy at the SWIR wavelengths for provision tothe illumination fiber 125. The illumination source 150 may, accordingto some example embodiments, be comprised of an incoherent source andfilters configured to filter the incoherent light provided by theincoherent source to collectively operate as the illumination source150. The illumination source 150 may be a laser, a light emitting diode(LED), or the like. According to some example embodiments, theillumination source 150 may be a super-luminescent diode (SLD). In someexample embodiments, the illumination source 150 may be coupled directlyto the illumination fiber 125. However, in some example embodiments, adiffuser 155 may be employed between the illumination source 150 and theillumination fiber 125. The diffuser 155 may be configured to diffuse orspread the light energy generated by the illumination source 150 acrossa surface in a relatively even fashion to minimize or remove highintensity areas or spots. By diffusing the light energy in this manner,the diffuser 155 may operate to reduce the spatial coherence of thelight energy generated by the illumination source 150, thereby reducingspeckle in images where the light energy used for illuminationoriginates from the illumination source 150. According to some exampleembodiments, to further diffuse the light energy from the illuminationsource 150, or to diffuse effects on the light energy caused bypropagation through the illumination fiber 125, a second diffuser may beplaced at the distal end 111 of the flexible elongate member 110.Further, according to some example embodiments, the diffuser 155 may bea dynamic diffuser that changes (e.g., rotates) or adjusts todynamically modify the diffusion of the light energy from theillumination source 150.

According to some example embodiments, to increase the illumination atdesired wavelengths, for example at the SWIR wavelengths, the imagingenvironment may be treated with a photoreactive chemical such as a dyeor particle. According to some example embodiments, the dye may be afluorescent dye that is specifically developed to fluoresce at the SWIRwavelengths and offers enhanced emission of light energy at the SWIRwavelengths. An example of such a dye is indocyanine green (ICG),whereas an example of a particle is an engineered quantum dot. The addedemission may cause increased intensity of light energy at the SWIRwavelengths to be received by the imaging detector 140 thereby improvingcontrast and image quality.

Additionally, according to some example embodiments, the illuminationassembly may also include capabilities to illuminate at wavelengthsother than SWIR wavelengths. In this regard, according to some exampleembodiments, the illumination assembly may include a separateillumination channel for, for example, visible light illumination. Inthis regard, the illumination assembly may include a visible lightsource that may be directed through another diffuser to an illuminationfiber that guides visible illumination light energy to a distal end ofthe flexible elongate member 110 to illuminate the object of interest165 with visible light. The visible light may be reflected from theobject and be received at the imaging detector 140 via the fiber opticbundle 115 to perform imaging in the visible spectrum, in addition tobeing capable of permitting imaging in the SWIR spectrum.

The flexible elongate member 110 may, according to some exampleembodiments, include mechanical features that permit the flexibleelongate member 110 to bend, flex, contort, or otherwise articulate intoa variety of positions. In this regard, according to some exampleembodiments, the flexible elongate member 110 may include or be disposedwithin one or more flexible mechanical moldable coils (e.g., gooseneckflexible metal tubing) that permit a user to bend or otherwisearticulate the flexible elongate member 110 into a desired position andthe flexible elongate member 110 may maintain that desired position.Additionally or alternatively, the flexible elongate member 110 may bemechanically controllable via a control interface to reposition theflexible elongate member 110. In this regard, the imaging apparatus 100may include mechanical controls 160 that may be operably coupled tocontrol cables 130 (e.g., wires) that are disposed within the flexibleelongate member 110. For example, the control cables 130 may be affixedto an inner surface of an external sheath of the flexible elongatemember 110 and may be movable to reposition the flexible elongate member110. In this regard, the mechanical controls 160 may include a userinterface in the form of a joystick or other type of directionalcontrols that may be physically connected to the control cables 130 suchthat, movement of the mechanical controls 160 causes movement of thecontrol cables 130 in the flexible elongate member 110 to position(e.g., bend or otherwise articulate) the flexible elongate member 110.According to some example embodiments, the control cables 130 may beaffixed in a manner such that the directional controls operate tomaneuver a portion near the distal end 111 (e.g., a tip) of the flexibleelongate member 110. According to some example embodiments, thedirectional controls may electrically connected to electromechanicalactuators (e.g., servos or the like) that receive electrical signalsfrom the directional controls and cause the electromechanical actuatorsto move thereby causing the control cables 130 that are connected to theelectromechanical actuators to move and position the flexible elongatemember 110.

Additionally, according to some example embodiments, the flexibleelongate member 110 may also include one or more accessory conduits 131.In regard, according to some example embodiments, an accessory conduit131 may be an open tube in the flexible elongate member 110 that wouldpermit a user to guide an item from the proximal end 112 of the flexibleelongate member 110 to the distal end 111 of the flexible elongatemember 110. For example, an accessory conduit 131 may be configured topermit a tool (i.e., a pincer, cutting tool, cauterizing tool, or thelike) to be inserted into a proximal end of the accessory conduit 131and pushed through the accessory conduit 131 to extend out of the distalend 111 of the accessory conduit 131 and the distal end 111 of theflexible elongate member 110. In this manner, a user may be capable ofperforming actions at the distal end 111 of the flexible elongate member110 while visualizing the environment at the distal end 111 of theflexible elongate member 110 via the operation of the imaging detector140 as further described herein. Additionally or alternatively, anaccessory conduit 131 may be configured to guide fluids (e.g., water) orgases (e.g., air) into a space at the distal end 111 of the flexibleelongate member 110 as required for certain applications of the imagingapparatus 100.

As indicated above, the flexible elongate member 110 may also include afiber optic bundle 115. According to some example embodiments, the fiberoptic bundle 115 of the flexible elongate member 110 may be operablycoupled between the proximal optics assembly 135 and a distal lens 120of the flexible elongate member 110. The distal lens 120 may be disposedat the distal end 111 of the flexible elongate member 110 and may beoptically coupled to the fiber optic bundle 115. According to someexample embodiments, the distal lens 120 may comprise a plurality ofoptic devices (e.g., lenses). According to some example embodiments, thedistal lens 120 may be a gradient index lens (i.e., GRIN lens) and maybe configured to focus light energy received at the distal end 111 ofthe flexible elongate member 110 onto the distal end of the fiber opticbundle 115 to be guided via the fiber optic bundle 115 to the imagingdetector 140. The distal lens 120 may be specifically designed forimaging of wavelengths throughout the SWIR wavelength. According to someexample embodiments, the distal lens 120 may be designed fortelecentricity in the image space, which may support coupling to theimaging fiber bundle 115. Also, the distal lens 120 may be embodied as acompact, small diameter lens (e.g. diameter of about 2 millimeters)thereby supporting a relatively small form factor and the capability toinvestigate narrowly constricted locations of interest for imaging. Thedistal lens 120 may be configured to focus light energy in the SWIRspectrum. The distal lens 120 may be relatively small in size forapplication at the distal end 111 of the flexible elongate member 110but still support high resolution imaging, particularly in the SWIRspectrum.

With respect the distal end 111 of the flexible elongate member 110,FIG. 2 illustrates a view of an example tip end 200. In this regard, thetip end 200 may include a casing 210 and a plurality of openings thatserve various purposes. The tip end 200 may include an illuminationopening 215 that is aligned with the illumination fiber 125 to outputillumination light energy from the illumination fiber 125. The tip mayalso include openings 230, 240, and 250, which may be accessory openingsthat align with a corresponding accessory conduit 131. Additionally, thetip end 200 may include an optical opening 220. The optical opening 220may be aligned with the fiber optic bundle 115 and the distal lens 120and configured to receive light energy reflected off of an object fordelivery to the imaging detector 140 via the distal lens 120 and thefiber optic bundle 115.

As mentioned above, the fiber optic bundle 115 may be specificallyconfigured to guide light energy in the SWIR spectrum to support imagingat SWIR wavelengths. Additionally, the fiber optic bundle 115 may beconfigured to support transmission of light energy at a SWIR wavelength,including, according to some example embodiments, multi-mode, nearsingle mode, or single mode transmission. According to some exampleembodiments, the fiber optic bundle 115 may be structurally designed toinclude a plurality of individual fibers (e.g., 321 of FIG. 3A) thatmake up the conglomerate fiber optic bundle 115. Referring to FIG. 3A,each fiber 321 may comprise, for example, a core 322 and cladding 323.The core 322 may be formed as a thread of glass or other energyconductor that is configured to propagate light energy in an efficientmanner. The cladding 323 may be disposed about and outer surface of thecore 322 in the form of a sheath. The cladding 323 may also be formed ofglass, but may provide an index of refraction that differs from theindex of refraction of the core 322.

To contribute to the ability to support operation at a SWIR wavelength,according to some example embodiments, a the fiber optic bundle 115 mayhave a defined relationship between the index of refraction of the core322 and the index of refraction of the cladding 323. In this regard, forexample, a percent decrease of the index of refraction of the cladding323 to the index of refraction of the fiber optic core 322 may bedefined. For example, the percent decrease of the index of refraction ofthe cladding 323 to the index of refraction of the fiber optic core 322may be between about 5% and 2% or in some cases 3.1%. Additionally, arelationship may be defined between the percent area of the fiber opticcore 322 to the fiber optic cladding 323 for a fiber 321. Each of theplurality of fiber 321 may define a cross-sectional area. For example,the percent area of the fiber optic core 322 to the fiber optic cladding323 may be about 40% for the core 322 and 60% for the cladding 323. Assuch, according to some example embodiments, to contribute to theability to support operation at the SWIR wavelengths, the cladding 323may have a greater portion of the cross-sectional area than the core322. According to some example embodiments, the cladding 323 may beabout 55% to 65% of the cross-sectional area of the fiber 321.

The fiber optic bundle 115 may be formed in a number of differentstructures to support operation at the SWIR wavelengths. According tosome example embodiments, the fiber optic bundle 115 may be a coherentimaging fiber bundle where individual fibers 321 of the fiber opticbundle 115 are aligned at the ends of the fiber optic bundle 115. Inthis regard, FIG. 3B illustrates one example of a fiber optic bundle 115that can support operation at the SWIR wavelengths. The fiber opticbundle 115 may comprise a proximal end 310, an intermediate portion 320,and a distal end 330. A length of the fiber optic bundle 115 may dependon the application for the imaging apparatus 100, but, according to someexample embodiments, the length of the fiber optic bundle 115 may be 1meter. The fiber optic bundle 115 may include a plurality of fibers 321,with each individual fiber 321 including a core 322 and cladding 323.The composite diameter of an individual fiber 321 (i.e., the diameterfrom and to an outer surface of the cladding 323) may have across-sectional diameter of, for example, 8 micrometers.

According to some example embodiments, the fiber optic bundle 115 mayprovide a wider field of view than a single mode fiber due to, at leastin part, the plurality of fibers 321 in the fiber optic bundle 115. Inthis regard, the plurality of fibers 321 may operate to increase theimage area relative to a single fiber. In some instances, a single fiberapproach may require a scanning mechanism for building up an image,whereas, according to some example embodiments, the fiber optic bundle115, with the plurality of fibers 321, may capture an image in a widerfield of view without the use of such as scanning mechanism or othersupporting components or processes that may be used to support effectivesingle mode operation with a single fiber.

At the proximal end 310 (and similarly the distal end 330), theplurality of fibers 321 may be arranged in an organized fashion as shownin the cross-sectional view of FIG. 4A, taken at A-A. According to someexample embodiments, the plurality of fibers 321 may be organized in ahexagonal arrangement or pattern. In this regard, the proximal end 310of the fiber optic bundle 115 may have a length (e.g., end length) whereferrule 311 may hold the plurality of fibers 321 in an aligned, parallelarrangement. According to some example embodiments, the bundle cladding420 may also assist with holding the plurality of fibers 321 in placeand may be comprised of, for example, air (e.g., through the use ofcladding spacers). According to some example embodiments, the bundlecladding 420 may also be comprised of glass that, for example, may beconfigured differently from the fibers 321. To hold the plurality offibers in the fixed position, a ferrule 311 may be crimped or otherwiseapplied to the proximal end 310. Although FIG. 4A illustrates across-sectional view of the proximal end 310, the distal end 330 may beidentical with the exception of being disposed at an opposite end of thefiber optic bundle 115 and held together by a ferrule 331. In exampleembodiments where the fiber optic bundle 115 is a coherent bundle,individual fibers 321 a and 321 b may be positioned in correspondinglocations on the proximal end 310 and the distal end 330. Further, asillustrated in FIG. 4A, fiber 321 a may be positioned adjacent to fiber321 b at the proximal end 310 and the distal end 330 of the fiber opticbundle 115.

With respect to the intermediate portion 320, the plurality of fibers321 may be held within a flexible sheath 324, which may extend into theproximal end 310 and the distal end 330. Within the intermediate portion320, the plurality of fibers 321 may be non-parallel and have anon-aligned arrangement. As shown in FIG. 3B, the parallel, alignedarrangement of the plurality of fibers 321 in the proximal end 310 andthe distal end 330 does not continue into the intermediate portion 320.In the intermediate portion 320, according to some example embodiments,adjacency relationships between the fibers 321 may be non-uniform, whichmay contribute to a reduction in crosstalk between the fibers 321 andtheir respective cores 322. The fibers 321 in the intermediate portion320 may, according to some example embodiments, be free to move relativeto each other and be reorganized into different relative orientationsdue to, for example, movement, bending, or otherwise articulation of thefiber optic bundle 115.

In this regard, for example, fibers 321 a and 321 b are shown as beingadjacent to each other at the proximal end 310 and the distal end 330,as shown in FIG. 4A. However, in the cross-sectional view of the FIG. 4Btaken at B-B of the fiber optic bundle 115 as shown in FIG. 3B, thefiber 321 a is not adjacent to the fiber 321 b. Because the fibers 321are permitted to move relative to each other in the intermediate portion320, rearrangement of the fibers 321 can occur, for example duringbending, flexing, or other type of articulation of the fiber opticbundle 115. As such, the fibers 321 a and 321 b do not remain adjacentto each other across the length of the fiber optic bundle 115 andtherefore the impact of crosstalk specifically between the two fibers isreduced, thereby promoting efficient propagation of light energy at theSWIR wavelengths.

As mentioned above, one technique for forming and arrangement ofnon-parallel or non-aligned fibers 321 in the intermediate portion 320may be via a leaching process. Examples of a fiber optic bundles 115that are leached, according to some example embodiments, include SchottNorth America, Inc.'s line of leached fiber optic bundles. To form aleached fiber bundle, the fibers 321 may be stacked, for example, in ahexagonal arrangement or pattern. A preform of the fiber optic bundle115 may be constructed that includes leachable spacers between thefibers 321. The preform of the fiber optic bundle 115 may then be drawnto a desired length and desired fiber and fiber core diameters.According to some example embodiments, the length of the fiber opticbundle 115 may be 1 meter and the diameter of the fibers 321 may be 8micrometers. The proximal and distal ends of the fiber optic bundle 115may be capped with a ferrule such that the proximal and distal endsremain coherent as described above. The leachable spacers may be solublein an etching acid. As such, when the intermediate portion 320 is dippedor otherwise subjected to the etching acid bath, the spacers may beleached away and the fiber cores 321 in the intermediate portion 320 maybe free to move relative to each other and be bent or flexed.

While the leaching process described above may be one technique forreducing crosstalk to support operation of the imaging apparatus 100 atthe SWIR wavelengths, other fiber optic bundle structures and techniquesmay also be employed. In this regard, an anti-crosstalk coating (e.g.,an energy absorbent coating) may be applied to each fiber core. In thismanner, crosstalk may be limited due to a reduction in the amplitude ofthe evanescent field generated by each fiber core.

As mentioned above, propagation of SWIR wavelengths in the fiber opticbundle 115 may also be supported, according to some example embodiments,due to characteristics of the individual fibers 321 of the bundle.Supported propagation modes within a fiber 321 may be governed by adimensionless quantity known as the V-number, which is defined as

${V = {\frac{2\pi}{\lambda}{aNA}}},$

where λ is the wavelength of light and a is the fiber optic core radius.NA represents the numerical aperture of the fiber 321, which dictatesthe largest acceptance angle that the fiber 321 will permit forpropagation of the light in the fiber optic core 322 of a step indexfiber (i.e., a fiber where the index of refraction is different betweenthe core and the cladding). The numerical aperture (dimensionless) isvalue that characterizes the range of angles over which light can beaccepted or emitted and is defined as NA=√{square root over (n_(core)²−n_(cladding) ²)}, where n_(core) ², is the index of refraction of thecore and n_(cladding) ², is the index of refraction of the cladding.Propagation mode confinement by an individual fiber 321 of the fiberoptic bundle 115 may be a factor that contributes to maintaining properimaging in the fiber optic bundle 115. In this regard, if a propagationmode is not confined to the individual fiber, crosstalk from fiber tofiber may operate to scramble the image. As is seen by the V-number,several parameters dictate the supported propagation modes of the fiber321. Specifically for SWIR wavelengths, according to some exampleembodiments, the radius of the fiber optic core 322 can dictate theability of the fiber 321 to support certain propagation modes. Accordingto some example embodiments, a fiber optic core radius that may supportpropagation modes for the SWIR wavelengths may have the area of thefiber optic core 322 that is 40% of the total cross-sectional area ofthe fiber 321, while the area of the cladding 323 (e.g., alone or withother surrounding materials) may be 60% of the cross-sectional area ofthe fiber 321. In some instances, this is in contrast to other fiberoptic bundles that do not support propagation modes for the SWIRwavelengths, whereby the fiber optic core to fiber optic cladding areapercentages may be 50% and 50%, respectively.

Further, to support propagation modes for the SWIR wavelengths, thefiber 321 may have a high NA value for optical fibers (e.g., an NA valuegreater than 0.25, such as 0.4), which is correlated with havingrelatively stronger propagation mode confinement in general.Additionally, a higher NA value may also have the ability to achievestronger confinement across a broader wavelength range than low NAfibers. The manipulation of the NA of the fiber 321 may be dependentupon the materials used for both the fiber optic core 322 and fiberoptic cladding 324. According to some example embodiments, a fiber 321with an index percent decrease between the fiber optic core and thefiber optic cladding of 3.1%, which may result in an NA=0.4. This is incontrast to, for example, a standard telecommunications single modefiber, which does not support propagation modes for the SWIR wavelengthsand has a fiber optic core to fiber optic index percent decrease betweenthe fiber optic core and the fiber optic cladding of 0.36%, resulting inan NA=0.19. The core radius and the NA may operate to increase theability of an individual fiber 321 to maintain light energy within thatfiber's core 322 over a larger range of wavelengths, including the SWIR.The core radius and the NA may also serve to confine the light in anindividual fiber optic core 322 over longer propagation distances, whichmay also limit the amount of light that escapes or leaks from the coreto the cladding 323 and on to a neighboring fiber 321 in the bundle 115.Such a reduced degree of light leakage from the individual fiber opticcore 322 into the cladding 323 may operate to reduce, for example,crosstalk particularly at longer wavelengths, such as those in the SWIR,where crosstalk is more prevalent.

Additionally, propagation of longer wavelengths, such as SWIRwavelengths, may also be supported, according to some exampleembodiments, by an index step size between the fiber optic cores 322 andthe cladding 323 being relatively large as compared to, for example,other fiber bundles. In this regard, the index of refraction of thefiber optic cores 322 may be different from the index of refraction ofthe cladding 323 by an amount that may be referred to as the index stepsize. A larger index step size between the core 322 and the cladding 323of the fiber optic bundle 115 may operate to increase an ability tomaintain light energy within the fiber optic cores 322 and limit theamount of light that escapes or leaks from the fiber optic cores 322.Such a reduced degree of light leakage from the fiber optic cores 322into the cladding 323 may operate to reduce, for example, crosstalk. Forlarger wavelengths, such as the SWIR wavelengths, the index step sizebetween the fiber optic cores 322 and the cladding 323 can be configuredto support the desired wavelength.

Additionally, leached fiber bundles may be able to propagate the SWIRwavelengths because the index step size between the core 322 and thecladding 323 may be rather large compared to other fiber bundles. When alarger the step size between core and cladding index of refraction ispresent, the fiber 321 may be better suited to contain the light withinthe core 322 because less light may leak into the cladding 323 whichreduces crosstalk. This may be especially true for larger wavelengths(e.g., SWIR wavelengths) as the step index size difference between thecore 322 and the cladding 323 may need to be greater to support thepropagation mode of interest. According to some example embodiments, anair clad fiber bundle may operate in this manner because the step inindex from the core glass to air is very large.

Finally, the spacing between the fiber cores, i.e. the claddingthickness, plays a large role in the interaction between cores. Thelarger the thickness the less likely interaction between cores canoccur; however, this comes at a cost of degraded resolution due to anassociated reduction in core packing. Additionally, according to someexample embodiments, dopants of the fiber optic cores 321 may alsooperate to support the operation of the fiber optic bundle 115 at theSWIR wavelengths. For example, according to some example embodiments,the fiber optic cores 321 may be doped with Germanium (GE) and thecladding 323, in the form of glass, may be doped with Fluorine (F) toincrease the index step size. Depending on dopant amounts, absorption inthe SWIR may be high, which would degrade the fiber optic cores' abilityto effectively transfer the light energy and thus an image.

According to some example embodiments, the diameters of the fiber opticcores 321 may be non-uniform. In this regard, some fiber optic cores 321may have larger or smaller diameters than other fiber optic cores 321.Differing diameters amongst the fiber optic cores 321 may also operateto reduce the amount of light energy leakage from a fiber optic core 321to another fiber optic core 321, when the fiber optic bundle 115 isconsidered in the aggregate. Since the different diameters may cause therespective fiber optic cores 321 to exhibit different supportedpropagation mode parameters, crosstalk may again be limited by theintroduction of fiber optic cores 321 of differing diameters.

Additionally, the spacing between the fiber optic cores 321 may also beconsidered to improve performance of the fiber optic bundle 115 at theSWIR wavelengths. In this regard, the spacing between the fiber opticcores 321 or the thickness of the cladding 323 may have an effect, andin in some instances a large effect, on the interaction between thefiber optic cores 321 with respect to, for example, crosstalk betweenthe fiber optic cores 321. In general, cladding 323 having a largerthickness and thus increased spacing between the fiber optic cores 321may permit less interaction between the fiber optic cores 321 and thusless crosstalk. However, according to some example embodiments, suchincreased spacing between the fiber optic cores 321 may cause degradedresolution due to an associated reduction in core packing (i.e.,closeness between the cores).

Additionally, according to some example embodiments, certain glass typesmay have the advantage of support propagation modes over smaller bendradii than those of other glass types. In this regard, fiber opticbundles 115 composed of soft glasses (e.g., glasses formed of two typesof lead silicate) may have the ability to support the SWIR wavelengthpropagation at a bend radius of 9 millimeters. This is compared toglasses of a more rigid variety, such as silica, that can only support abend radius of 60 millimeters. Bend loss associated with the differingglasses can be attributed to the NA of the fiber 321, with again higherNA fibers 321 suffering less bend loss than lower NA fibers.Accordingly, crosstalk may be reduced at smaller bend radii, which againcan be beneficial to the transmission of the SWIR wavelengths. Softglasses may have higher NAs and are therefore less susceptible to bendloss compared to the more rigid glasses.

The components described herein, have been described with respect tosupporting operation of an imaging apparatus at the SWIR wavelengths.Additionally, according to some example embodiments, the componentsdescribed herein may also support operation at wavelengths other thanSWIR wavelengths. For example, according to some example embodiments, animaging apparatus may support imaging at NIR wavelengths as well as SWIRwavelengths. As such, according to some example embodiments, an imagingapparatus may be configured to perform imaging operations at differentwavelengths to generate multi-band imaging (e.g., SWIR and NIR imaging).

Having described example embodiments of the imaging apparatus 100 in amore general sense, FIG. 5 illustrates an example imaging apparatus inthe form of a handheld portion of an endoscope 500, according to someexample embodiments. In this regard, the endoscope 500 may have a distalend 501 and a proximal end 502. Further, the endoscope 500 may comprisedistal tip 510, a flexible elongate member 520, a proximal opticsassembly 530, an imaging detector 540, and a handle 550. In this regard,the distal tip 510 may house a distal lens (e.g., distal lens 120) andbe affixed to a distal end of the flexible elongate member 520. Theflexible elongate member 520 may include a fiber optic bundle (e.g.,fiber optic bundle 115) and an illumination fiber (e.g., illuminationfiber 125). The proximal optics assembly 530 may be affixed to aproximal end of the flexible elongate member 520 and may be structuredand configured to operate in the same manner as the proximal opticsassembly 135. Further, the imaging detector 540 may be structured andconfigured to operate in the same manner as the imaging detector 140.Finally, the handle 550 may be included to facilitate user manipulationof the endoscope 500 and the flexible elongate member 520 of theendoscope 500.

In some embodiments, a focusing capability may be built into distal tip510 at distal end 501 of endoscope 500. For example, FIG. 9 includesexample focusing device 900. Focusing device 900 may include microstepper motor 910, lead screw 920, and lens holder 930. Micro steppermotor 910 may drive distal lens 120 or distal lens 720 back and forth toprovide focus (or imaging) to various objects at different distancesfrom the distal end 111. In some embodiments, the focusing device 900,including the micro stepper motor 910, has a maximum diameter of 3.4 mm.Lead screw 920 is attached to the shaft of micro stepper motor 910 andmay spin clockwise or counterclockwise. In some embodiments, lens holder930 holds distal lens 120 or distal lens 720 and/or is coupled to distallens 120 or distal lens 720. Lens holder 930 may be coupled to microstepper motor 910 via lead screw 920. As lead screw 920 spins, lensholder 930 may ride up and down lead screw 920 and changes the focus ofthe image data collected allowing for more accurate imaging.

In one embodiment, the plurality of fiber 321 may be rigidly coupled tothe housing of micro stepper motor 910 such that the coherent bundle(e.g., fiber 321) stays fixed in place behind the moving lens. Light(e.g., SWIR wavelengths) may be focused using distal lens 120 andpropagate through the fiber bundles as described above.

In another embodiment, the housing of micro stepper motor 910 may becoupled to or include the SWIR imaging sensor 715. Distal lens 720 mayfocus the light to SWIR imaging sensor 715, while micro stepper motor910 may allow adjustment of the focus to enable accurate datacollection.

FIG. 10 illustrates an example of a distal tip of endoscope 1000. Distaltip of endoscope 1000 may include endoscope 500, flexible elongatemember 520, distal tip 510, and distal end 501. FIG. 10 shows an exampleembodiment illustrating various components from FIGS. 1, 5, 7, and 9. Inone embodiment, distal tip of endoscope 1000 includes diffuser 155 or755 that diffuses light in, for example, the SWIR spectrum, fromillumination fiber 125 or 725 or from compact SWIR illumination source790. Distal tip of endoscope 1000 may also include stepper motor 910that spins lead screw 920 (not shown in FIG. 10) on which nut 1010slides up and down changing the focus for distal lens 120 or distal lens720 held in place by lens holder 930. FIG. 10 also depicts placement ofthe fiber optic bundle 115 or SWIR imaging sensor 715 that are opticallycoupled to distal lens 120 or distal lens 720 and receives, for example,light in the SWIR spectrum propagated through diffuser 155 or 755 andreflected off an object of interest 165.

FIG. 6 illustrates a block diagram of an example method 600 for imagingaccording to various example embodiments. In accordance with thedescription above, according to some example embodiments, the examplemethod 600 may comprise, at 610, generating light energy at a shortwaveinfrared (SWIR) wavelength by an illumination source, and, at 620,guiding the light energy, via an illumination fiber, to a distal end ofa flexible elongate member to illuminate an object with the light energyat the SWIR wavelength. Additionally, at 630, the example method 600 maycomprise receiving imaging light energy at the SWIR wavelength from theilluminated object at a distal lens of the flexible elongate member. Inthis regard, the imaging light energy may be light energy at the SWIRwavelength guided by the illumination fiber and reflected off of theobject. Further, at 640, the example method 600 may comprise focusingthe imaging light energy at the SWIR wavelength onto a fiber opticbundle via the distal lens. In this regard, the fiber optic bundle maycomprise a plurality of fibers. Additionally, the example method maycomprise, at 650, guiding the imaging light energy at the SWIRwavelength through the plurality of fibers of the fiber optic bundle toa proximal end of the fiber optic bundle, and, at 660, receiving theimaging light energy at the SWIR wavelength at an imaging detector.

Additionally, according to some example embodiments, the fiber opticbundle of the example method 600 may comprise a portion (e.g., anintermediate portion) where the plurality of cores are disposed in anon-parallel arrangement, for example, due to a leaching process.Additionally or alternatively, the fiber optic bundle of the examplemethod 600 may comprise a first fiber core and a second fiber core andthe first fiber core may be disposed adjacent to the second fiber coreat the distal end and the proximal end of the fiber optic bundle.However, the first fiber core need not be adjacent to the second fibercore at an intermediate portion of the fiber optic bundle.

Additionally or alternatively, the example method 600 may comprisepassing the light energy generated by the illumination source through adiffuser prior to guiding the light energy to the distal end of theflexible elongate member to reduce spatial coherence of the light energygenerated by the illumination source. Additionally or alternatively,according to some example embodiments, the example method may alsocomprise guiding the imaging light energy at the SWIR wavelength throughthe fiber optic bundle at the SWIR wavelength as a multi-mode, nearsingle mode, or single mode transmission. Additionally or alternatively,each fiber of plurality of fibers of the fiber optic bundle may comprisea core and cladding and each fiber defines a cross-sectional area.According to some example embodiments, about 55% to 65% of thecross-sectional area of a fiber of the fiber optic bundle may beattributed to the cladding. Additionally or alternatively, an index ofrefraction for the cladding may be about 5% to 2% lower than the indexof refraction of the core. Additionally or alternatively, the examplemethod 600 may comprise, according to some example embodiments, causingthe flexible elongate member to bend or otherwise articulate in responseto actuation of a mechanical control to move a control cable in theflexible elongate member. According to some example embodiments, theexample method 600 may also comprise, according to some exampleembodiments, performing image processing on signals corresponding to theimaging light energy at the SWIR wavelength received at the imagingdetector to generate an image of the object. Additionally oralternatively, the example method 600 may include adding a fluorescentdye to the object that reflects light energy at the SWIR wavelength.

FIG. 7 illustrates a block diagram of another example imaging apparatusaccording to some example embodiments. The imaging apparatus 700 may beany type of imaging device including, but not limited to, an endoscope,fiberscope, or the like. In this regard, the imaging apparatus 700 or aportion thereof, may be a handheld device with, for example, a handle topermit a user to position and operate the device. The imaging apparatus700 may be distinguished from imaging apparatus 100 for performingdirect imaging, as imaging apparatus 700 may not include a coherentimaging fiber bundle, such as fiber optic bundle 115, and may include,for example, an extremely small SWIR platform at the distal tip 711. TheSWIR platform may include, for example, SWIR imaging sensor 715, distallens 720, and distal polarization optics 785.

The imaging apparatus 700 may include a flexible elongate member 710that includes a proximal end 712 and a distal end 711. The flexibleelongate member 710 may be configured to flex, bend, or otherwisearticulate into various positions while supporting optical imagingfunctionalities. The orientation and positioning of the flexibleelongate member 710 may be controllable by a user to position a distalend 711 of the flexible elongate member 710 in a desired position toperform an image capture of an object of interest 165. In this regard,the flexible elongate member 710 may have a distal end 711 which may,when in use, be closer to the object of interest 165 for image capture,and the flexible elongate member 710 may have a proximal end 712, whichmay be opposite the distal end 711 and may be physically coupled to ahandle.

SWIR imaging sensor 715 (e.g., a SWIR sensitive compact imager (FocalPlane Array)) may be included in flexible elongate member 710 or may beoperably coupled to distal end 711 of flexible elongate member 710. TheSWIR imaging sensor 715 may include a Focal Plane Array (FPA) where theimaging pixels sit in an array. The SWIR imaging sensor 715 may beoptically coupled to distal lens 720 (which itself may be part of orcoupled to flexible elongate member 710). Distal lens 720 may be anobjective lens that images directly onto SWIR imaging sensor 715. Distallens 720 focuses reflected light from the object of interest 165 backonto the FPA of SWIR imaging sensor 715. Distal lens 720 may be, forexample, a gradient index lens (i.e., GRIN lens). Distal lens 720 mayhave a short focal length and an anti-reflection coating for SWIR.Distal lens 720 may be part of or optically coupled to distalpolarization optics 785. The distal polarization optics 785 maycondition light reflected off of, for example, object of interest 165prior to directing light to distal lens 720. In this regard, accordingto some example embodiments, the distal polarization optics 785 mayinclude lenses shaped to filter, condition, and polarize light energy inthe SWIR spectrum reflected off the object of interest 165 for input tothe SWIR imaging sensor 715.

When imaging an object up close (sub-inches to inches) the providedillumination can sometimes cause specular reflections off of the object.These specular reflections can overwhelm the image and appear as brightspots in the field of view. When up close, where the object fills theimage field, this can limit the ability to see anything, and inparticular, fine image details. Using a plurality of polarizers reducesthese specular reflections. In one example embodiment, the light sourcemay be initially polarized (e.g., using proximal polarization optics780) before it illuminates the object and then, the light reflected ofthe object of interest, may be polarized using a second polarizer oranalyzer (e.g., distal polarization optics 785) to control the intensityof the reflected light, especially the polarized specular reflections,that come back into the distal lens 720 and SWIR imaging sensor 715.Proximal polarization optics 780 and distal polarization optics 785 maybe adjustable. If the polarization is not desired, for example, thepolarizers may be oriented such that they are aligned along the sametransmission axis.

SWIR imaging sensor 715 may be a device that is capable of capturinglight energy, including light energy in the SWIR spectrum, andconverting the received light energy into electrical signals fordelivery to processing circuitry (e.g., processing circuitry 745) forimage processing to develop a corresponding image. In this regard, theSWIR imaging sensor 715 may be configured to receive imaging lightenergy at a SWIR wavelength that has been reflected from an object ofinterest 165 and focused on the SWIR imaging sensor 715 via distal lens720. According to some example embodiments, the SWIR imaging sensor 715may be configured to perform imaging at a wide range of wavelengths,which may operate to permit imaging in both the visible spectrum and theSWIR. According to some example embodiments, the SWIR imaging sensor 715may include an image processor and may be configured to perform some orall image processing local to the SWIR imaging sensor 715. The SWIRimaging sensor 715 may comprise any type of digital camera, sensor array(e.g., charge coupled devices, active pixel sensors, etc.), or the likewith sensitivity in the SWIR region of the electromagnetic spectrum.According to some example embodiments, an SWIR imaging sensor 715 thatcomprises a digital camera may be specifically configured to operate tocapture images at the SWIR wavelengths. In some embodiments, SWIRimaging sensor 715 may have a maximum diameter of 0.5 inches. In someembodiments, SWIR imaging sensor 715 may have a resolution of 640×512 ormore and in other embodiments, the SWIR imaging sensor 715 may have amaximum resolution of 320×256 or less,

According to some example embodiments, the flexible elongate member 710may include an illumination fiber 725, or a bundle of illuminationfibers. The illumination fiber 725 may be an optical fiber that, in someexample embodiments, is disposed within the flexible elongate member 710and extends from the proximal end 712 of the flexible elongate member710 to the distal end 711 of the flexible elongate member 710. Theillumination fiber 725 may be configured to deliver or guide lightenergy from an illumination source 750 to the distal end 711 of theflexible elongate member 710 for output into the environment about thedistal end 711 of the flexible elongate member 710 to illuminate, forexample, an object of interest 165. According to some exampleembodiments, the illumination fiber 725 may be configured to guide lightenergy in the SWIR spectrum from the illumination source 750 to thedistal end 711 of the flexible elongate member 710. According to someexample embodiments, the illumination fiber 725 may be a multi-modefiber.

While the illumination fiber 725 may be disposed within the flexibleelongate member 710, the illumination fiber 725 may be a component of anillumination assembly. According to some example embodiments, theillumination assembly may include the illumination fiber 725, anillumination source 750, and proximal polarization optics 780.

In another embodiment, a compact SWIR illumination source 790 may beplaced at the distal tip 711 of the flexible elongate member 710. Thecompact SWIR illumination source 790 may include or be opticallyconnected to diffuser 755. In this embodiment, the compact SWIRillumination source 790 replaces the functionality of the illuminationfiber 725, the proximal polarization optics 780, and the proximal endillumination source 750. In this embodiment, the illumination fiber 725,the proximal polarization optics 780, and the proximal end illuminationsource 750 may not be included in imaging apparatus 700.

The proximal polarization optics 780 may include one or more lensesconfigured to condition (e.g. focus) light energy received from anillumination source 750. In this regard, according to some exampleembodiments, the proximal polarization optics 780 may include lensesshaped to filter, condition, and polarize light energy in the SWIRspectrum from the illumination source 750 for input to the illuminationfiber 725.

In some embodiments, illumination source 750 and proximal polarizationoptics may be housed in the handle coupled to the flexible elongatemember 710. Alternatively, in some other embodiments, the functionalityof illumination source 750 and proximal polarization optics 780 may beincluded in a compact SWIR source that is bundled with illuminationfiber 725 inside of the flexible elongate member 710.

At distal end 711, illumination fiber 725 may be operably coupled todiffuser 755, which according to some example embodiments, may be staticor mechanically moveable or electroactively moveable. Diffuser 755 maybe included in or coupled to distal end 711 of flexible elongate member710. The diffuser 755 may be configured to diffuse or spread the lightenergy initially generated by the illumination source 750 (andpropagated through illumination fiber 725) or compact SWIR illuminationsource 790 across a surface in a relatively even fashion (e.g.,uniformly) to minimize or remove high intensity areas or spots. Bydiffusing the light energy in this manner, the diffuser 755 may operateto reduce the spatial coherence of the light energy generated by theillumination source 750, thereby reducing speckle in images where thelight energy used for illumination originates from the illuminationsource 750 or to diffuse effects on the light energy caused bypropagation through the illumination fiber 725. Further, according tosome example embodiments, the diffuser 755 may be a dynamic diffuserthat changes (e.g., rotates) or adjusts to dynamically modify thediffusion of the light energy from the illumination source 750.

According to some example embodiments, the imaging apparatus 700 mayinclude or be operably coupled to processing circuitry 745. Processingcircuitry 745 may be configured to receive electronic signalscorresponding to an image capture of light energy and generate an image.The processing circuitry 745 may be configured to transmit the image toa display 146 (e.g., a liquid crystal display that may be stand-alone, acomponent of smartphone or tablet, or the like) via wired or wirelesslyfor viewing by a user for the purpose of analyzing the image, forexample, to make a diagnosis, or to navigate the flexible elongatemember 710 into a desired position to capture, for example, an image ofan object of interest 165. The processing circuitry 745 may include, forexample, a processor and a memory, and the processor may be configuredto execute instructions, code, or commands stored on the memory to causethe processing circuitry 745 to perform the functionalities of theprocessing circuitry 745 described herein. Alternatively, oradditionally, the processor may be a hardware defined device configuredto cause the processing circuitry 745 to perform the functionalities ofthe processing circuitry 745 describe herein, and may be embodied as,for example, a field programmable gate array (FPGA), an applicationspecific integrated circuit (ASIC), or the like. In some embodiments,processing circuitry 745 may be housed in flexible elongate member 710or in the handle coupled to flexible elongate member 710. In otherembodiments, processing circuitry is included and part of the SWIRimaging sensor 715.

The illumination source 750 may be any type of light generating devicethat can generate light energy at the SWIR wavelengths for provision tothe illumination fiber 725. The illumination source 750 may, accordingto some example embodiments, be comprised of an incoherent source andfilters configured to filter the incoherent light provided by theincoherent source to collectively operate as the illumination source750. The illumination source 750 may be a laser, a light emitting diode(LED), or the like. According to some example embodiments, theillumination source 750 may be a super-luminescent diode (SLD). In someexample embodiments, the illumination source 750 may be coupled directlyto the illumination fiber 725. However, in some example embodiments,proximal polarization optics 780 may be employed between theillumination source 750 and the illumination fiber 725.

Additionally, according to some example embodiments, the illuminationassembly may also include capabilities to illuminate at wavelengthsother than SWIR wavelengths. In this regard, according to some exampleembodiments, the illumination assembly may include a separateillumination channel for, for example, visible light illumination. Inthis regard, the illumination assembly may include a visible lightsource that may be directed through another diffuser to an illuminationfiber that guides visible illumination light energy to a distal end ofthe flexible elongate member 710 to illuminate the object of interest165 with, for example, visible light.

The flexible elongate member 710 may, according to some exampleembodiments, include mechanical features that permit the flexibleelongate member 710 to bend, flex, contort, or otherwise articulate intoa variety of positions. In this regard, according to some exampleembodiments, the flexible elongate member 710 may include or be disposedwithin one or more flexible mechanical moldable coils (e.g., gooseneckflexible metal tubing) that permit a user to bend or otherwisearticulate the flexible elongate member 710 into a desired position andthe flexible elongate member 710 may maintain that desired position.Additionally or alternatively, the flexible elongate member 710 may bemechanically controllable via a control interface to reposition theflexible elongate member 710. In this regard, the imaging apparatus 700may include mechanical controls 760 that may be operably coupled tocontrol cables 730 (e.g., wires) that are disposed within the flexibleelongate member 710. For example, the control cables 730 may be affixedto an inner surface of an external sheath of the flexible elongatemember 710 and may be movable to reposition the flexible elongate member710. In this regard, the mechanical controls 760 may include a userinterface in the form of a joystick or other type of directionalcontrols that may be physically connected to the control cables 730 suchthat, movement of the mechanical controls 760 causes movement of thecontrol cables 730 in the flexible elongate member 710 to position(e.g., bend or otherwise articulate) the flexible elongate member 710.According to some example embodiments, the control cables 730 may beaffixed in a manner such that the directional controls operate tomaneuver a portion near the distal end 711 (e.g., a tip) of the flexibleelongate member 710. According to some example embodiments, thedirectional controls may electrically connected to electromechanicalactuators (e.g., servos or the like) that receive electrical signalsfrom the directional controls and cause the electromechanical actuatorsto move thereby causing the control cables 730 that are connected to theelectromechanical actuators to move and position the flexible elongatemember 710.

Additionally, according to some example embodiments, the flexibleelongate member 710 may also include one or more accessory conduits 731.In regard, according to some example embodiments, an accessory conduit731 may be an open tube in the flexible elongate member 710 that wouldpermit a user to guide an item from the proximal end 712 of the flexibleelongate member 710 to the distal end 711 of the flexible elongatemember 710. For example, an accessory conduit 731 may be configured topermit a tool (i.e., a pincer, cutting tool, cauterizing tool, or thelike) to be inserted into a proximal end of the accessory conduit 731and pushed through the accessory conduit 731 to extend out of the distalend 711 of the accessory conduit 731 and the distal end 711 of theflexible elongate member 710. In this manner, a user may be capable ofperforming actions at the distal end 711 of the flexible elongate member710 while visualizing the environment at the distal end 711 of theflexible elongate member 710 via the display 146. Additionally oralternatively, an accessory conduit 731 may be configured to guidefluids (e.g., water) or gases (e.g., air) into a space at the distal end711 of the flexible elongate member 710 as required for certainapplications of the imaging apparatus 700.

FIG. 8 illustrates a block diagram of an example method 800 for imagingaccording to various example embodiments. In accordance with thedescription above, according to some example embodiments, the examplemethod 800 may include, at 810, generating light energy, using a laser,LED, or the like, at a shortwave infrared (SWIR) wavelength by anillumination source at a proximal end of a flexible elongate member orat a compact SWIR source at a distal tip of the elongate member.

From 810, flow may move to 820, which includes guiding the light energyfrom the illumination source at the proximal end, via an illuminationfiber, or from the compact SWIR source placed at the distal tip, to adistal end of a flexible elongate member to illuminate an object withthe light energy at the SWIR wavelength. In some embodiments, the lightenergy at the SWIR wavelength is passed through a diffuser coupled tothe distal end of the flexible elongate member prior to illuminating theobject.

From 820, flow may move to 830, which includes receiving imaging lightenergy at the SWIR wavelength from the illuminated object at a distallens of the flexible elongate member. In this regard, the imaging lightenergy may be light energy at the SWIR wavelength originally from theillumination source at the proximal end or from the compact SWIR sourceplaced at the distal tip which is reflected off of the object.

From 830, flow may move to 840, where the imaging light energy at theSWIR wavelength is focused directly onto a SWIR sensitive compact imager(Focal Plane Array) via a distal lens.

From 840, flow may move to 850, which includes transmitting image data(e.g., the electrical output signal), via wired or wireless, that isrepresentative of the image itself from the SWIR imaging sensor throughthe flexible elongate member to a display. This may include transmittingthe image data to an image processor and processing the images prior tosending to a display. The display may be a standalone display unit suchas a smartphone, tablet, or other portable computing and display device.From 850, flow may move to 860 and end. Additionally or alternatively,the example method 800 may include adding a fluorescent dye to theobject that reflects light energy at the SWIR wavelength.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

That which is claimed:
 1. An imaging apparatus comprising: a flexibleelongate member having a distal end and proximal end, the flexibleelongate member comprising: a shortwave infrared (SWIR) imaging sensor;a distal lens optically coupled to the SWIR imaging sensor and disposedat the distal end of the flexible elongate member, the distal lensconfigured to focus light energy at a SWIR wavelength onto the SWIRimaging sensor; an illumination source configured to provide lightenergy at the SWIR wavelength at the distal end of the flexible elongatemember for output to illuminate an object; and one or more controlcables disposed within the flexible elongate member enabling movement ofthe flexible elongate member; and a handle coupled to the flexibleelongate member; and mechanical controls operably coupled to the controlcables for directing the flexible elongate member.
 2. The imagingapparatus of claim 1, wherein the illumination source is disposed at theproximal end of the flexible elongate member, and wherein the flexibleelongate member further comprises illumination fiber that directs lightenergy at the SWIR wavelength from the illumination source to the distalend of the flexible elongate member.
 3. The imaging apparatus of claim1, wherein the flexible elongate member comprises a compact SWIRillumination source disposed at the distal end of the flexible elongatemember.
 4. The imaging apparatus of claim 1, wherein the flexibleelongate member further comprises a diffuser configured to reducespatial coherence of the light energy generated by the illuminationsource.
 5. The imaging apparatus of claim 1, wherein the flexibleelongate member further comprises: a first polarization optic opticallycoupled to the illumination source, wherein the first polarization opticpolarizes the light energy at the SWIR wavelength; and a secondpolarization optic optically coupled to the distal lens, wherein thesecond polarization optic is adjustable to control an intensity of thelight energy at the SWIR wavelength reflected off of the object.
 6. Theimaging apparatus of claim 1, wherein the SWIR imaging sensor has aresolution of 640×512 and a maximum diameter of 0.5 inches.
 7. Theimaging apparatus of claim 1, wherein the light energy at the SWIRwavelength has a wavelength between about 1.0 micrometer to about 1.7micrometers.
 8. An imaging apparatus comprising: a distal end; aproximal end; a shortwave infrared (SWIR) imaging sensor disposed at thedistal end; a lens disposed on the distal end, the lens configured tofocus light energy at a SWIR wavelength on the SWIR imaging sensor; SWIRanti-reflective coating disposed on the lens; and an illuminationassembly configured to output illumination at the SWIR wavelengthadjacent to the distal end toward an object, wherein the SWIR imagingsensor is configured to receive imaging light energy at the SWIRwavelength reflected from the object and focused through the lens. 9.The imaging apparatus of claim 8, further comprising illumination fiberthat directs light energy at the SWIR wavelength from the illuminationassembly to the distal end, wherein the illumination assembly isdisposed at the proximal end.
 10. The imaging apparatus of claim 8,wherein the illumination assembly is disposed at the distal end.
 11. Theimaging apparatus of claim 8, wherein the illumination assemblycomprises an illumination source configured to provide light energy atthe SWIR wavelength, the illumination source being a super-luminescentdiode.
 12. The imaging apparatus of claim 8, wherein the SWIR imagingsensor has a resolution of 640×512 and a maximum diameter of 0.5 inches.13. The imaging apparatus of claim 8 further comprising: a firstpolarization optic optically coupled to the illumination assembly,wherein the first polarization optic polarizes light energy at the SWIRwavelength; and a second polarization optic optically coupled to thelens, wherein the second polarization optic is adjustable to controlintensity of the light energy at the SWIR wavelength reflected off ofthe object.
 14. A method comprising: generating light energy at ashortwave infrared (SWIR) wavelength by an illumination source;projecting the light energy at a distal end of a flexible elongatemember to illuminate an object with the light energy at the SWIRwavelength; receiving imaging light energy at the SWIR wavelengthreflected from the illuminated object at a distal lens of the flexibleelongate member; focusing the imaging light energy at the SWIRwavelength onto a SWIR sensitive compact imager via the distal lens; andtransmitting image data from the SWIR imaging sensor to a display. 15.The method of claim 14, further comprising: guiding the light energy viaan illumination fiber from a proximal end to the distal end.
 16. Themethod of claim 14, wherein the light energy is generated in the SWIRwavelength by a compact SWIR source disposed at the distal end.
 17. Themethod of claim 14, further comprising passing the light energygenerated by the illumination source through a diffuser prior toilluminating the object to reduce spatial coherence of the light energygenerated by the illumination source.
 18. The method of claim 14,further comprising: polarizing the light energy generated by theillumination source with a first polarization optic; polarizing theimaging light energy from the illuminated object with a secondpolarization optic; and removing specular reflections in the imaginglight energy from the illuminated object by adjusting the firstpolarization optic and the second polarization optic.
 19. The method ofclaim 14 further comprising adding a fluorescent dye to or near theobject, the fluorescent dye being configured to emit light energy at theSWIR wavelength.
 20. The method of claim 14 further comprisingperforming image processing on signals corresponding to the imaginglight energy at the SWIR wavelength received at the SWIR sensitivecompact imager to generate an image of the object.